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Discussion Starter #1
you know the more and more I study pics I relize that what I have going on my bike may not be so out there. Just as an example: we all know BMW's are great handeling bikes, but whats different from what I'm doing? Maybe somepeople are just naturaly sceptics, but experiance is key. I'm a newbie what do I know.

I still relize that my bike needs work. Thanks to you guys I'm getting great ideas for future projects on this bike.





If you build it they will ride - ill.


Edited by - Anythingillegal on Mar 02 2007 12:27:41 AM
 

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Discussion Starter #3
Yes the frame is different but the shock angle is nearly the same. And it must work.

If you build it they will ride - ill.
 

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Discussion Starter #4
Thanks for the example pic<img src=icon_smile_wink.gif border=0 align=middle>

If you build it they will ride - ill.
 

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I didn't see that you had added your suspension picture.

Those two set-ups couldn't be more diffrent!

The paralever and monolever BMW's run that set-up because it's a single sided swingarm AND shaft driven. It simply has no other place to go. The ohlins on my monolever Beemer is easily 3x the size of the shocks on any twin shock bike I have. It's a monster. Check out the angle, more in-line with the swingarms movement.

Why do you want to run the shock at that angle? Form should follow function, if you want to try something diffrent study the suspension designs of the past 20-30 years, you'll see a trend. If you look at the angles on the beemer the shock will compress as the wheel travels upward. On your mock up the shocks would fold as the wheel traveled upward. You want to consider how all the parts work together. Check out eurospares.com and Tony Faole's site. Plenty more ideas to scheme on.

Not trying to be negative just giving some input.

...and one last bit of info to think about. That stupid ohlins for the beemer costs more than most of the Hondas I ride.


BORN TO LURK, FORCED TO WORK.
www.NYCvinMoto.com
www.VinMoto.org

Edited by - ROSKO on Mar 02 2007 12:57:08 AM
 

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the shock angle will only be ok with better shocks......im tellin you, the setup you got on there now is gonna leave yer arse bloody...yuck...
 

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correct me if I am wrong but I don't think the incomplete BMW started life as a monolever (and uses an already design suspenison that is set up to work that way - he didn't just lay over his oid shocks).

I am sure you have great fab skills, but you nees to go out and rea a book on motocycle chassis design and set up before you start doing "radical" stuff.
 

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Note that the BMW shock top end mount also resides in a very very strong location of the frame. Numerous tubes coming together in a triangulated setup. Your setup has the top mount in the middle of a single tube....it will bend that tube in a heartbeat.

I know you have your heart set on that look...but if we were mean and nasty guys we'd just tell you "yeah that will work great" and then snicker when it breaks. Last year I extened my race bike swingarm 2" and left the shock mounts in the same place....just two inches more angle, and it made the suspension noticably softer.

JohnnyB
 

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not to mention that you have cut off a huge section of the frame fear of the engine and now there is no cross brace tying it together back there (just noticed that). Your swingarm pivot bolt is not the only thing structurally tying the bottom end of your frame together - bad idea. The more I look at your bike the more it currently looks like a death trap.

http://www.tonyfoale.com/

"motorcycle handeling and chassis design" buy it, read it, and do it right. I am sure you are a a very good metal worker but the fact they we now have two threads telling you your shock design is functionally a bad idea should be a good indicator that you don't know dick about motorcycle chassis structure and design (not that I know all that much either beut even I can see a couple of different flaws) and it is time to get educated.


And another thing I think your rider position is a little too far rearward. Looking at it again the rider is just before the tire which is ok (gives a little rearward weight bias, not great but ok) but if you put a passenger on it their weight will actually be past the centerline of the axle (if you use the stock cbr passenger seat location) meaning wheelie. I am guessing that this is going to be a solo seat motorcycle but still extending your swingarm another two inches isn't such a bad idea.

and another thing - who told you BMWs were good handeling bikes? Sure they are good street bikes till the ground clearance runs out but it took a lot of work for imcomplete to get their BMW to handle decently. being a good street bike usually means they are medicore handeling bikes on the track, and vice versa. I have heard from all accounts that incomplete's BMW is a pain in the ass to ride on the street.

Edited by - Geeto67 on Mar 02 2007 12:26:43 PM
 

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Just to add fuel to the fire, the reason that the suspension won't work well at that angle is because the leverage that the axle has on the shock changes as the swingarm moves - depending on the starting and ending angles you could have either progressive or digressive spring rate changes.

Now, if you've got lots of time and money, and Tony Foale's expensive book, you could set it up to be progressive with exactly the right angle and shock/spring combos. On the other hand, that still does not solve the scary engineering issues others have brought up.

If you look closely at the early 80s production superbike racers, just before they went to mono-shocks, you'll see that they laid them down, sometimes drastically, on the racers. The details are all-important here, though, and just cranking them over won't do squat.
 

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This is just my subjective opinion, so don't take it seriously. But I would say that the styling of your mock-up bodywork clashes with the styling of the rest of the bike. You've done a really good job of fitting the tank and tail section together, but overall it looks like you have grafted 80's/90's bodywork on to a 70's chassis.

Look at your motor, frame and wheels: they have pure old school styling (standard styling from the 50's to the late 70's). Now look at your proposed bodywork. It has a modern-sportbike look (strictly 80's/90's/00's). It's like furnishing your victorian house with bauhaus furniture - it may be interesting, but mainly because of the incongruity.
 

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Discussion Starter #12
All right I know I don't know shit about suspension setup. So in regards to everyone's comments I thank you guys. It's nice to have the support of knowledged riders. In the future I will have pics of the bike with less angle on the shocks or better shocks/springs, but any suggestions on what would be a good deg? I think I read 45deg is o.k. from straight up and down.

As for the subframe cons. I will be triangulating and bracing quite a bit more. It needs it nodoubt but thanks for the concern. What you see is completely for mock up for the shocks and cbr tail section. I'll have more pics.

And for the styling, I think it's about personality. It's my bike and I want to express my self in this way. As spoke about in other forums - it's about what a cafe bike is all about and the guy who rides it. See you on the street!

If you build it they will ride - ill.
 

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Hey, no doubt the shocks look cool layed down like that. And it's probably still doable with more frame mods. I'd think 45 degrees would be acceptable with the right shocks, a sturdy top mount and good swingarm bushings. Technically not a real efficient setup, but then a lot of custom bikes aren't particular efficient but still look cool.
JohnnyB
 

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Discussion Starter #15
I changed the shock angle to 45deg and I noticed a large improvement in stiffness. I think I like the angle, gives the style but allows the suspension to do it's job.

I've done some more work to the sub frame, any suggestions?



If you build it they will ride - ill.
 

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lookin' good. Two nit-picky things... get the rest of the paint off the weld areas? (sorry, I'm a stickler) and Maybe throw a sleeve inside that butt joint? A lot of stress from rider weight there.

Thats all I've got. Shop looks good, whadda y'all be makin' there?

BORN TO LURK, FORCED TO WORK.
www.NYCvinMoto.com
www.VinMoto.org
 

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Hehe...now you're just being a smart ass :)
Yes that setup would certainly work....in fact it would probably work for a cement truck it would be so strong :)
Probably could have gotten away with a single extra tube that goes from the top shock mount to the right angle in the frame just above and behind the carb tops. That would transfer the load up to the main frame.
But yeah...looks way more suitable and pretty trick. If you aren't worried about the weight of a couple of extra tubes it looks like it will work to me.
Put some nice aftermarket shocks on there with some good adjustments and you could probably dail in a decent working rear end.
JohnnyB
 

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Discussion Starter #18
The tube I decided to use on this bike has about half or less the wall thickness as our V-twin frames (close to stock Honda). The tube is very light, but your right I didn't need that much. Thought I'd tack it all together to see what it would look like. I should took a pic from the top, looks good from that angle too.

Yeah yeah yeah the paint comes off when I final tig.

The shop I work for is called Conspiracy Cycle Works (CCW)we mainly deal in the after market, custom bikes, race bikes, but we do just about anything. That jeep in the back ground is ugly as hell but built to do the job.

I have access to cheap parts almost 20% cheaper than any one else-if anyone is interested, but don't waste my time if your not serious I work for a living!

If you build it they will ride - ill.
 

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Can you get Honda parts? I need a couple carb kits for my cb350. And since you're so close, I'd even buy you a pint for hooking me up - there's a couple decent pubs in Dexter. I've never heard of CCW. Where are you guys located?
 

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much much better. I applaud your ability to look past the quasi-insults and really make an effort to incorporate the useful bits of what was said.

Looks much better and will work much better too. keep us posted.
 
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